1. Field of the Invention
The present invention relates to high-volume production of products having a printed circuit board encapsulated by mechanical shells.
2. Brief Description of the Related Art
Prior products which are formed of a housing which encloses electronic components have typically encapsulated the printed circuit board (PCB) with two plastic parts produced by separate tools. The trimming of the tools is approached in two ways. The two tools are produced in pairs, that is, one supplier or toolmaker is responsible for trimming the two different tools against each other. This approach can offer a good solution to the problem of forming housing to close mechanical and cosmetic tolerances, as it usually guarantees that the parts fit nicely together. Consequently, very tight tolerance requirements can be met. This first solution implies, however, that a significant amount of risk is concentrated with one supplier or toolmaker; if something goes awry with the sole supplier's manufacturing facility or die tools, the entire production of the product stops.
Alternatively, the risk of a significant production stoppage can be spread out among a number of suppliers. In this alternative risk spreading scheme, several different suppliers for the tools produce the housings for the product, i.e., no single one of the suppliers produces a pair of tools. If something goes wrong with any one of the multiple suppliers, the consequences are relatively minor compared with the first solution, outlined above. However, the tolerances between the parts produced by different suppliers must be, by necessity, significantly rougher to assure that the parts will actually fit together. Consequently, the product will more likely have larger gaps between its parts and larger cosmetic mismatches (e.g., structure and color differences between its parts). This can lead, in turn, to malfunctioning of electromechanical connections within the product, and also can result in a final product which is less attractive.
U.S. Pat. No. 4,939,792 describes a moldable/foldable radio housing onto which four solderable printed circuit patterns are vacuum deposited on the interior and exterior of a base and cover, which are joined by a hinge. U.S. Pat. No. 4,703,160 describes a casing structure of a portable electronic appliance, in which four panels are joined by hinges and are releasably attached when folded together. U.S. Pat. Nos. 5,432,676 and 5,541,813 describe a portable telephone having a case with a wiring member in a molded plastic hinge, in which the hinge is opened and closed during regular use, and the hinge is formed of a material different from that used to form the rest of the case. U.S. Pat. No. 3,580,650 describes a cabinet for holding, e.g., a complete radio, in which four sections are joined together by hinges that can be opened and closed during regular use. EP 547 994 A1 describes a stamped sheet of metal which is folded upon itself and joined with tabs to form a housing. None of these prior devices resolve the problems outlined above.